In the manufacture of an electronic circuit having conductive structures extending to a surface of a layer, tolerances allow some degree of protrusion above, or recession below, the surface of the layer. That is, the resulting conductive structures are more or less planar to the surface of the layer, but with some allowable variation (i.e. planar deviation between the surface of the structures and the surface of the layer). Too much variation, however, is undesirable and can negatively affect the functional integrity of the circuit. What is needed is a facility for achieving greater planarity between the upper surfaces of conductive structures and a layer in which the structures reside.